I just had an idea for making stats more useful than numbers go up. This is one example, but the concept could be copied across a lot of stats. Maybe temple raiding itself is locked behind doing this quest first.
I have mentioned some different training paths. So take for example sending a harem girl to train with the nuns to increase purity stats (which in turn decreased lewd). This could be a method to unlock the quest to take the ritual scroll from the temple. Maybe this is how you unlock the damage / heal combo spell.
Cannon would be she learned about it during her studies and brought the info back to you.
Mechanics would be once she reaches a certain stat level or number of days training in the cloister, you get a cut scene of her finding it and getting interrupted by the guardian priestess as she reaches out toward it. So she comes back to tell you about it.
Cut scene doesn't have to be a single pic. Could be one pic with her reaching out to the scroll, then a 2nd pic with the priestess standing in the doorway, 3rd pic of her whispering in the hero's ear or reporting to him before his throne.
If consistent look of the hero across the game is an issue, could get creative with cropping or again do a multi photo story line like having the pic of the master sitting on his throne, then a scene of her bowing or on her knees before him to make the art generation easier by not trying to do everything in a single pic.
Same multi pic story line method might help with other scenes you're having trouble generating art for.